1. Field of the Invention
The present invention relates to a method of making a photosensor such as an image pickup tube, a one- or two-dimensional line sensor, and more particularly to a method of making a photosensor having a photoconductive layer essentially made of an amorphous semiconductor.
2. Description of the Prior Art
An image pickup tube as one of photosensors will now be described. An image pickup tube using a photoconductive layer of an amorphous semiconductor is described in, for example, Japanese Patent No. 902189 corresponding to Japanese Patent Unexamined Publication JP-A No. 49-246l9. In order to use an image pickup tube of such type at high sensitivity, techniques in which a high electric field is applied across the photoconductive layer of the image pickup tube to thereby cause avalanche multiplication of charges in the photoconductive layer are disclosed in ITEJ (Institute of Television Engineers of Japan) Technical Report, Vol. 10, No. 45, pp. 106, ED-'87 (1987).